docs: def build_filename(self, binary):
          """Return the proposed filename with extension for the binary."""
  
          return '%(TIMESTAMP)s%(BRANCH)s%(DEBUG)s-%(NAME)s' % {
              'TIMESTAMP': self.timestamp + '-' if self.timestamp else '',
              'BRANCH': self.branch,
              'DEBUG': '-debug' if self.debug_build else '',
              'NAME': binary}